Drafting tool



Jan. 3,1939. Y E SHATTOW I 2,142,765

DRAFTING TOOL Filed Nov. 15, 1936 INVENTOR. gmi/ 6am I Patented Jan. 3, 1939 ammo sra'rss PATENT orrme 3 Claims.

This invention is a drafting tool and seeks, among other objects, to provide a tool of the described class which will, by means of one instrument, enable a draftsman to do work which at the present time requires two or more devices; yet, as will be apparent from the drawing and annexed specification and claims, is not a mere combination of the tools now used.

Among other objects this invention provides a draftsmans instrument which is compact and easy to use.

A still further important object of my invention is to provide a means whereby all the various curves and angles, necessary in drawing, may be accurately ascertained and used in drafting lines in accurate and unshifting position.

A further important object is the provision of a means whereby a line may be accurately divided into equal segments Without the usual experimental and frequently inaccurate use of the conventional dividers.

A still further important object of my device is the provision of means of accurately determining or fixing the slant of lines used in forming letters in drafting.

Other and further objects will be apparent from the drawing and from the specification which follows.

On the drawing:

Fig. 1 is a top elevational view of my invention showing generally its parts and illustrative of the various handy scales, etc., to which my invention lends itself.

Fig. 2 is a top elevational View of my invention on a drawing board and in conjunction with a conventional T-square, particularly illustrating how the arm portion will pass above the T-square.

Fig. 3 is a cross sectional View taken on the line 33 of Fig. 1, illustrating the rivet which holds the body and arm portions in close but r0- tatable juxtaposition.

As shown on the drawing:

The numeral illustrates the base section which, as shown in Fig. 1, comprises a triangle, preferably a 45 isosceles triangle, having formed therein a triangular aperture the edges of which are parallel to the outer edges of said triangle, and in preferred form having indicated thereon the plurality of inch scales or divisions indicated by the numerals l3 and N3, the proportional dividing scales indicated by numeral [4, the lettering angle guide, indicated by numeral 15, and the plurality of computed scales for proportional reduction of drawings, indicated by the numerals 20.

The numeral l I indicates the movable arm section which is fastened to the base or main portion ill by a rivet 12, adapted to hold the parts in close, but rotatable juxtaposition.

As shown on the drawing, the arm section or portion II has formed therein a plurality of irregularly curved apertures and has an irregularly curved forward periphery, forming the principal curved outlines used in drafting. At its upper rearward part, it has a shoulder portion Ila having a straight edge formed at an obtuse angle to the rearward straight perpendicularly extending portion of the said arm section H, such that when the said straight edge is placed in registry with the outer rear edge of the left leg of said base triangle portion 10 the perpendicularly extending straight rearward edge 16 of said arm portion is exactly perpendicular to the base line of triangle Ill, and. the mark on the protracter [1, which forms the forward part of said shoulder portion of arm section I I, is then in complete registry with the inner edge of the right leg of said triangle. The straight rearward edge of said arm portion of section II may, as shown on the drawing, be marked off into inches or the like for measurement purposes.

It will be apparent from the above description and the drawing that this device may be used, as are the conventional drawing accessories, as a triangle, protractor, French curve, ruler, box Wood and proportional scale. The additional and distinctive uses of this device and wherein it differs from the use of the above enumerated devices per se or in combination lies in the combination of a triangle forming a base and an arm portion rotatably fastened thereto which arm portion will form a Wide variety of angles when rotated in its various angular relations to the said base triangle.

One particularly valuable use is in lettering. By shifting the rearward straight perpendicular edge It of arm portion II to the points marked L on the drawing the letters formed by using the perpendicular edge will be 67 in slant either right or left. By shifting the protractor l1 into registry with the inner edge of the right leg of the triangle, any desired slant of letter may be obtained for right-slant lettering. Perpendicular lettering can be made by putting the straight edge I 6 in perpendicular position as that position has been previously described.

The device herein disclosed may be used as a proportional divider and will aid in accurately segmenting a line of any given length. For instance, suppose it were desired to segment a line 20 inches in length into seven equal parts with, say, a device as herein disclosed measuring six inches at its base. The user then projects 45 lines from each end of the line to be segmented to an apex forming a triangle. This device, being used with a T-square as a base, may then be moved up until the 45 projected lines aforementioned coincide with the ends of the base of the triangular portion of my device. The distance between the lines at this point will then be exactly six inches. Then by rotating the arm carrying the edge Hi to that portion of the triangle base at which 1/7 is indicated, registering it therewith, and marking the drawing, then projecting a line from the apex of the triangle drawn as aforementioned through the marking aforementioned and to the line to be segmented, will accurately indicate 1/? of the line which is to be segmented. Further segments may then be stepped off with a conventional divider.

A still further important object which may be accomplished by my device is the accurate proportional reduction of drawings. For instance, let us say that an original drawing made to the scale of 1 inch to 1 foot is to be reduced to say, /2 inch to 1 foot. The base line of the internal triangular aperture is placed in registry with the line to be reduced. The point of intersection of the appropriate proportional markings 20 on the leg of the triangle is then noted and a straight line is drawn through this mark by means of the T- square. The line visible in the internal triangular aperture, from inner leg to inner leg of the triangular aperture, will then measure 2 inches. Suppose 3 feet 3 inches 'is to be indicated on the reduced drawing (which on the original drawing will be 3% inches, on the scale of 1 inch equals 1 foot). By rotating arm portion II to the 3 inch mark on the base section the perpendicular edge It of arm II will intersect the line of the reduced drawing at a point in proper proportion to the selected scale and may then be indicated by a dot or line.

It will be obvious from the drawing and above detailed description that I have invented a device which is novel and eifective for the purposes set forth.

Various changes may be made in the embodiment of the invention herein specifically described Without departing from or sacrificing any of the advantages of the invention or any features thereof and nothing herein shall be construed as limitations on the invention, its concept or structural embodiment as to-the Whole or any part thereof except as defined in the appended claims.

I claim:

1. In a drafting tool the combination of a fiat triangle having a triangular aperture formed therein, said triangle forming a fiat base, a plurality of spaced apart markings on the lower portions of said base representing angles of predetermined degree and proportional segments of the base line of said triangle and aperture, and an arm member pivotally mounted on the apex of said triangle and rotatable in spaced relation in a plane above said triangle, its lower extremity intersecting said triangle base and spaced markings in spaced and angular relation thereto.

2. In a drafting tool the combination of a fiat isosceles triangle, forming a fiat base, having a triangular aperture therein, the edges of said aperture being parallel to the outer periphery of said triangle, a plurality of spaced apart markings on the base of said triangle and adapted to indicate various angles and proportional segments of the base of said triangle and an arm pivotally mounted to the apex of said triangle and rotatable in a plane immediately above said triangle, said arm having a straight edge adapted to guide the drawing of lines on drawing material through the aperture in said triangle, said arm intersecting the base of said triangle at predetermined angles and on predetermined proportional markings, and adapted to be a guide in lettering or in determining proportionate segments of a line.

3. In a drafting tool the combination of a flat 45 isosceles triangle having a triangular aperture formed therein the edges of which are parallel to the legs and base of said triangle, said triangle forming a flat base, a plurality of spaced apart markings adapted to represent predetermined angles or proportionate segments of a line paraliel to the base line of said triangle when said triangle is centered thereon, and an arm member pivoted at the apex of said triangle and rotatable in a plane above and in close juxtaposition to said triangle and adapted to over-extend the base line of said triangle, and be placed in registry with the markings of said triangle base, said arm having one straight lateral edge, said straight edge adapted to determine the angles of letters formed by the guidance thereof or to determine, in conjunction with certain of said markings, the segments of a segmented line parallel to and centered on the base of said triangle.

EMIL E. SHATTOW. 

